Existing systems and methods for measuring the thickness variation and shape of a wafer may not provide a desired level of accuracy and sensitivity to meet the demands of the next generation of semiconductors. As semiconductor technology advances, so do the wafer sizes and patterns on wafer surfaces, resulting in a need for improved systems with greater accuracy.
One existing method for determining the thickness variation and shape of a wafer may involve obtaining a distance map between each side of the wafer and two corresponding reference flats. The existing systems and methods may compute the thickness variation and shape of the wafer from this data by comparing it to calibrated distance maps between the two reference flats and each side of the wafer. Two maps, one corresponding to each side of the wafer, may be combined to compute the thickness variation and the shape of the wafer. This process may not provide a desired level of accuracy and sensitivity to meet requirements for systems measuring the thickness variation and shape of a wafer.
Therefore, there exists a need for a method and apparatus for measuring the thickness variation and shape of a wafer.